1. Field of the Invention
The present invention relates to a semiconductor light emitting device and a nitride semiconductor light emitting device, and particularly relates to a semiconductor light emitting device and a nitride semiconductor light emitting device which are capable of suppressing the deterioration of crystallinity of an active layer and have high light emitting efficiency and high current density.
2. Description of the Background Art
The structure of a conventional nitride semiconductor light emitting device is generally a structure in which an n-type nitride semiconductor layer, an n-type or an undoped nitride semiconductor active layer, and a p-type nitride semiconductor layer are layered in this order on a substrate.
In a nitride semiconductor light emitting device with this structure, since the nitride semiconductor active layer is an n-type and the effective mass of an electron is smaller than that of a hole, the hole concentration in the nitride semiconductor active layer at high current density becomes extremely small compared with the electron concentration. Therefore, since excess electrons approach into to the region of the p-type nitride semiconductor layer and recombine with holes in the region of the p-type nitride semiconductor layer at a ratio in which the electrons cannot be ignored in the region of the nitride semiconductor active layer, there has been a problem that light emitting efficiency of the nitride semiconductor light emitting device decreases.
Hence, in Japanese Patent Laying-Open No. 2004-064080, a nitride semiconductor light emitting device is proposed in which at least one of the nitride semiconductor active layers is made to be p-type.